1. Field of the Invention
The present invention relates to a method for storing a substrate cleaning brush, which brush is used in a substrate cleaning apparatus in which various types of substrates, such as semiconductor wafers, glass substrates for liquid display apparatuses or photomasks, or substrates for optical disks, are held horizontally and rotated about a vertical axis while applying cleaning liquid to the substrates and subjecting them to a cleaning action with the brush. More particularly, the present invention is directed to a method for storing a substrate cleaning brush having a brush body which is formed of a sponge-like porous material.
2. Description of the Prior Art
An example of a conventional substrate cleaning apparatus and a conventional method for cleaning a substrate with a cleaning brush will be briefly described. A substrate, such as a semiconductor wafer, is held horizontally on a top surface of a spin chuck by way of a vacuum. Cleaning liquid is applied to the substrate while rotating the substrate on the spin chuck about a vertical axis. A brush rotation shaft of a brush holding arm is rotated so that the cleaning brush which is fixed to the rotation shaft is kept in a downward orientation by the brush holding arm and is lowered from an upper position to a lower position while the cleaning brush rotates. A bottom edge of the cleaning brush is moved close to a surface of the substrate. With the bottom edge of the cleaning brush touching the surface of the substrate, the rotating cleaning brush is brought into movable contact with the surface of the rotating substrate whereby the substrate is cleaned. In such a substrate cleaning apparatus, the cleaning brush is replaced with the same or a different type of cleaning brush in accordance with the type of substrates to be cleaned or the cleaning requirements. To this end, the cleaning brush is structured so that it can be mounted to, and detached from, the brush rotation shaft of the brush holding arm.
The cleaning brush is comprised of a brush holder and a brush body. Although the brush body generally has a number of bristles disposed on a bottom surface thereof, a brush body of a hydrophilic sponge-like porous material, which, for example, may be manufactured from polyvinyl alcohol, may also be used. A cleaning brush which employs a brush body made of a porous material is conventionally housed, stored and transported in a dry vessel. At a semiconductor production plant or the like, a user sufficiently impregnates the brush body with cleaning liquid, such as pure water, to wet the brush body before using the cleaning brush. The user then cleans a dummy substrate with the brush and, thereafter, uses the brush in a production line.
However, a brush body made of a hydrophilic sponge-like porous material is hard and has no elasticity when it is dry. Hence, it takes a considerably long time to impregnate the brush body with pure water or the like to make the brush body soft enough for use. It may take as long as from thirty minutes to six hours before the brush is usable in a production line.
In addition, particles may adhere to a brush body made of a porous material during storage or transportation of the cleaning brush. Thereafter, when the cleaning brush is used to clean substrates, the cleaning brush may cause adhesion of the particles to a surface of a substrate being cleaned. It is also possible that the brush body will create very fine dust during storage or transportation of the cleaning brush because the brush body becomes hardened. The dust may adhere to a surface of a substrate when the substrate is cleaned.
Further, a conventional brush body may become deformed when the wet, newly manufactured brush body is dried, stored or transported and, thereafter, moistened again prior to using the cleaning brush.